The present invention relates to a sheet clamp apparatus, more particularly to a photoconductor sheet clamp apparatus capable of clamping a photoconductor sheet to a drum for use with an electrophotographic copying apparatus and unclamping the photoconductor sheet therefrom securely and easily.
In the electrophotographic copying apparatus, a selenium photoconductor and a zinc oxide photoconductor are used as representative light sensitive materials. The former is excellent in photoconductivity and dielectric characteristics and can be used repeatedly in the electrostatic image formation process. It is, however, expensive. On the other hand, the zinc oxide photoconductor is cheaper than the selenium photoconductor, but its life time for use in the electrostatic image formation is not as long as that of the selenium photoconductor. However, recently the zinc oxide photoconductor has been improved so that its life time is lengthened. Therefore, the zinc oxide photoconductor has an advantage of being lower in cost.
Accordingly, when the zinc oxide photoconductor is used in the electrophotographic copying apparatus in the form of a sheet to be wound around a drum, it has to be exchanged more frequently with a fresh zinc oxide photoconductor in comparison with the selenium photoconductor, still due to the life time of the zinc oxide photoconductor.
Supposing that the life time of the zinc oxide photoconductor sheet is approximately 500 copies in terms of the number of copies that can be made acceptably by the photoconductor, obviously it has to be exchanged frequently in practical use.